Interlock mechanisms

ABSTRACT

An interlock unit ( 10 ) for use with at least one other like unit ( 11 ) to form an interlock mechanism has a top face ( 13 ) and opposed pairs of side walls ( 12 ) with at least one runner bar ( 17, 18 ) mounted in the unit for lateral sliding movement. An actuator ( 14, 15, 22 ) is supported on the top face ( 13 ), to effect lateral sliding movement of the runner bar ( 17, 18 ). One wall of the unit is provided with one part ( 27 ) of a two-part connector with the other part ( 33 ) on the opposed wall whereby two similar units may be joined together by relative sliding movement of the two units in the plane of the side walls ( 12 ). Joining together of two units ( 10, 11 ) in this way also joins together the runner bars ( 17 ) or ( 18 ) of the two units such that sliding motion of the runner bar ( 17 ) of one unit ( 10 ) is transferred to the runner bar ( 17 ) of the connected unit ( 11 ), for at least one direction of sliding movement of the runner bars ( 17 ).

[0001] This invention relates to an interlock unit for use with at leastone other like interlock unit, to form an interlock mechanism. Theinvention further relates to an interlock mechanism assembled from suchinterlock units.

[0002] Interlock mechanisms are widely used in various industries, toensure equipment is operated safely and in accordance with pre-definedprocedures. Most such mechanisms are key-operated, but they can includeone or more other operating devices, such as a solenoid supplied withelectrical power depending upon the setting of a remote switch. Theswitch may, in turn, be operated for example by a machine guard or someother moveable component.

[0003] A typical interlock mechanism has a plurality (and at least two)actuators, and usually at least two key-operated actuators, themechanism being arranged so that an activity can be undertaken only whenat least one key has been inserted into its respective actuator and istrapped there, to prevent its use elsewhere. For instance, there may betwo such actuators arranged so that one key must always be present inits actuator. If a key is required for example to open a door to aprotected area, that key may be removed only if another key used tocontrol an activity in that protected area is inserted into the otheractuator and is trapped there.

[0004] The principles of key-interlock mechanisms of the kind describedabove are well known in the art and form no part of the presentinvention, as such. Consequently, they will not be described in furtherdetail here.

[0005] A problem of an interlock mechanism of the kind described aboveis that in general the mechanism must be constructed especially for eachintended application. In particular, the interlinking of thekey-operated actuators by internal runner bars must specifically bedesigned to provide the required functionality. Though standardisedparts may be used in assembling the mechanism, it is usually necessaryexpressly to design the mechanism for the intended use and then tomanufacture parts just for that one design. In turn, this leads torelatively high costs, and the inability to re-use the interlockmechanism in the event that the original use becomes redundant.

[0006] It is a principal aim of the present invention to provide meanswhereby an interlock mechanism may be assembled to any particular designfor a proposed use, from discrete building blocks each of which has anindividual actuator for example configured to accommodate a key andinteract with the other blocks.

[0007] According to the present invention, there is provided aninterlock unit for use with at least one other like interlock unit toform an interlock mechanism, which interlock unit has a top face andopposed pairs of side walls, at least one runner bar mounted in the unitfor lateral sliding movement, an actuator for effecting lateral slidingmovement of the runner bar which actuator is supported on the top faceof the unit, one wall of an opposed pair thereof being provided with onepart of a two-part unit connector and the opposed wall with the otherpart of the connector, which connector is arranged to permit two similarunits to be joined together by relative sliding movement of the twounits in the plane of the side walls to inter-engage the respectiveconnector parts, the runner bar of one unit being engageable with therunner bar of a connected unit to transfer sliding motion thereto forsliding movement of the runner bar of said one unit in at least onedirection.

[0008] It will be appreciated that a complete interlock mechanism may beassembled from a plurality of interlock units of this invention andgiven the required functionality for the intended purpose, by adjustingthe internal components of each interlock unit. By having the runnerbars of the respective units automatically engaging the runner bars ofthe adjacent units, the motion of one runner bar may be transferred tothe mechanism of the other units in the assembly so as to control thefreeing or the locking of other actuators of those other units.

[0009] For many applications, each actuator includes a receptor for aremovable key, whereby the insertion of a suitably coded key into thereceptor permits the turning of the receptor by the key, and so theoperation of the actuator. It is also possible to employ one or moreremotely controlled actuators, such as a solenoid or motor-drivenactuator. Such an actuator may be controlled by a remote switch,operated for example by a machine guard or some other moveablecomponent.

[0010] It is preferred that the unit connector allows the joiningtogether of two units by relative sliding movement therebetween, in adirection normal to the top surfaces of the two units. This may beachieved by having the one part of the unit connector formed as are-entrant slot on the one face of the unit, preferably opening into thebottom wall of the unit. Then, the other part of the connector maydefine a projection of a complementary form to the re-entrant slot sothat the slot of one unit and the projection of a second unit areinterengageable by relative sliding movement of the units, along thelength of the slot.

[0011] The projection may be of circular form, so that the unit havingthe projection may take up a required angular orientation with respectto the unit having the slot. In the alternative, a peg and slotarrangement may be formed on the two units being joined together so thatwhen fully connected, the units have a relationship pre-defined by thepeg and slot.

[0012] To permit automatic interengagement between the runner bars ofadjacent units on joining the units together, each runner bar should bearranged for sliding movement in a direction normal to the opposed pairof side walls of a unit carrying the connector parts. A preferredarrangement has two runner bars arranged mutually at right angles andfor sliding movement with respect to each opposed pair of side walls. Insuch a case, each opposed pair of side walls should carry respectiveconnector parts, so that a second interlock unit may be joined to anyone of the four side walls of a first unit, the respective runner barsthen automatically interengaging.

[0013] Further to facilitate the automatic interengagement of the runnerbars of adjacent units, it is convenient for there to be respectiveapertures formed through the connector parts of the opposed pairs ofside walls, with the runner bars arranged for sliding movement in thoseapertures. To this end, the two runner bars of one unit may beoppositely cranked to permit them to cross over each other in thecentral region of the unit, whilst having the axes of all four apertureslying in the same plane.

[0014] In the simplest case, motion may be transferred from a runner barof one unit to the runner bar of an adjacent unit by having the adjacentends of the respective runner bars simply abutting each other; thus,either runner bar may push but not pull the other. Preferably, however,the runner bars interengage to permit either bar to push or pull theadjacent bar and to this end a coupling piece may be provided on one endof the runner bar of one unit and which is engageable with the opposedend of the runner bar of a connected unit. To this end, both endportions of each runner bar may be provided with a connector blockprofiled to permit the interconnection thereto of the coupling piece andto hold the coupling piece against relative axial movement.

[0015] Each unit preferably is provided with a cam arranged to effectmovement of the (or each) runner bar of the unit upon rotation of thecam. Such a cam may form a part of the actuator, so as to be turned forexample by the key receptor, on using the appropriate key. The insertionof a key into the receptor and then turning of the key to rotate thereceptor traps the key therein and also turns the cam to move the runnerbar. This action may free for rotation the cam, and so also thereceptor, of an adjacent unit so that the key of that unit may be turnedand released from the adjacent unit.

[0016] This invention extends to a key-interlock mechanism wheneverassembled from two or more interlock units of this invention asdescribed above.

[0017] By way of example only, one specific embodiment of akey-interlock mechanism of this invention and assembled from twointerlock units will now be described in detail, reference being made tothe accompanying drawings, in which:

[0018]FIG. 1 is an isometric view of the mechanism comprising twokey-interlock units interlinked and with one key inserted;

[0019]FIG. 2 is an isometric internal view of the two units, with thecover plates removed for clarity;

[0020]FIG. 3 is an isometric view on an enlarged scale of one of theunits, with various parts removed for clarity;

[0021]FIGS. 4A and 4B are respectively isometric and side views of arunner bar used in a unit;

[0022]FIGS. 5A and 5B are two different isometric views of a couplingpiece for interlinking two runner bars;

[0023]FIGS. 6 and 7 are plan views on the two units with a runner bar ofone unit connected to the runner bar of the other unit, and with therunner bars in two different settings, respectively;

[0024]FIG. 8 is a view similar to that of FIG. 6, but with analternative coupling piece;

[0025]FIG. 9 is a cut-away isometric view of a unit incorporating asolenoid-operated actuator; and

[0026]FIG. 10 shows a latch bolt end unit which may be coupled to one ofthe units of FIG. 1.

[0027] Referring initially to FIG. 1, there is shown an interlockmechanism arranged in accordance with this invention and assembled fromtwo similar interlock units 10 and 11 each having a key-operatedactuator. Each unit is generally of square cross-sectional shape and hasopposed pairs of side walls 12 and a cover plate 13. Each cover plateincludes a central rotatable key receptor 14 pre-configured to accept akey 15 of a particular design and coding. Thus, the two key receptors 14of the two units 10 and 11 should differ internally, so that each mayaccept only a particular key 15. Each key receptor is arranged so thatit may accept a key when in a particular rotational setting, and whenturned from that setting by an inserted key, the key may no longer beremoved.

[0028] The two key receptors are interlinked within the interlock unitsto control the rotation thereof and so the possibility of the insertionand removal of keys. In the arrangement shown in FIG. 1, the right handkey cannot be removed from its receptor, nor can the receptor be turnedby the key to the key-removal position. The left hand key may beinserted into its receptor and turned to lock the key in its receptor;and when turned, the right hand key may be turned and removed.

[0029] A key-interlock mechanism as described above is well known in theart and is widely used in many areas of industry. Since the function anduse of such a key-interlock mechanism forms no part of the presentinvention, it will not be described in further detail here.

[0030]FIGS. 2 and 3 shown internal constructional details of theinterlock units 10,11 as well as the connector by means of which the twounits 10,11 are joined together. In each unit, there are two runner bars17,18 arranged for sliding movement across the unit, respectivelybetween opposed pairs of side walls 12. Thus, the line of sliding actionof one runner bar 17 is at 90° to that of runner bar 18. The side wallshave respective apertures 19 slideably to support the runner bars, thefree ends of which may thus project through the apertures 19 in the sidewalls. The axes of all four apertures 19 lie in the same plane, therunner bars being cranked in opposite senses in order to allow thecentral regions 20 thereof to overlie one another and slide with respectto the other. Each central region is generally in the form of arectangular plate, with a rectangular opening 21 formed therethrough.The runner bars 17,18 may be identical, but are mounted with opposedfaces uppermost.

[0031] In each unit, a cam 22 is centrally mounted within the openings21, for rotation about a vertical axis. The cam has a pair of lobes23,24 respectively engageable with the central regions 20 of the tworunner bars 17,18 of that unit. The cam profile of each lobe is arrangedso that rotation of the cam may cause sliding movement of the associatedrunner bar along its length, in one direction or the other, dependingupon the initial setting and angular movement of the cam. Moreover, therunner bars may also block rotational movement of the cam, againdepending upon the relative disposition of the cam and the two bars.

[0032] The cam 22 has a central hole 25 of square cross-sectional shape,engageable by a square drive-shank (not shown) on the underside of thekey receptor 14 of the cover plate 13 for the unit. Thus, rotation of akey inserted into the receptor causes the cam 22 of that unit to rotateand so to move the runner bars 17,18 of that unit.

[0033] The opposed pairs of side walls 12 of each unit are provided withthe complementary parts of a connector adapted to permit two similarunits to be joined together, as shown in FIGS. 1 and 2. There is formeda slot 27 in one side wall 28 (FIG. 3) which slot opens into the bottomplane 29 of the unit and is closed at its upper end, adjacent the top ofthe unit, the upper end having a semi-circular profile as best seen inFIG. 3. The slot 27 has a re-entrant form, defined by aninwardly-directed lip 30, formed around the edge of the slot 27.

[0034] The side wall 31 opposed to side wall 28 (and so also side wall32, between side walls 28 and 31) is formed with a circular projection33, the projection having a flange 34 formed around its periphery. Theprojection 33 is discontinuous in its upper region, so as to provide achannel 35 leading to the central region of the projection, for apurpose to be described below. The projection 33 and flange 34 areconfigured so as to permit interengagement with a slot 27 of a secondunit, such that the two units will be joined together with theirrespective side walls 28,31, in frictional engagement with one anotherand held against axial separation. Though not shown, a peg may beprovided within the slot 27 to locate in channel 35 so as to hold thetwo units against relative rotational movement. In the alternative, nosuch peg need be provided and the two units may be positioned atdifferent relative angular dispositions, for unusual applications.

[0035] Referring particularly to FIGS. 4A and 4B, the two end portions37,38 of each runner bar 17,18 are formed with a transversely extendingconnector block 39,40, the orientation of that block at one end portion37 being at 90° to the orientation of the other block 40 on the otherend portion 38. Each connector block is of dove-tail cross-section topermit the connection thereto of a coupling piece 41, as shown in FIGS.5A and 5B. This coupling piece has a pair of dove-tail grooves 42,43extending thereacross at right angles to one another, there being acentral aperture 44 through the coupling piece to permit the directinterengagement of the end planes of the connector blocks 39,40 of twoadjacent runner bars connected by the coupling piece 41.

[0036] The coupling piece 41 is used by sliding the coupling piece on toconnector block 40 on end portion 38 of a runner bar—that is to say, theconnector block the length of which runs generally parallel to thebottom plane 29 of the associated interlock unit. The coupling piece 41will thus not fall off the connector block under gravity and groove 43will extend generally vertically, as shown at the right hand side inFIG. 3. Then, on joining a second interlock unit to the first interlockunit, by interengaging projection 33 on that second interlock unit intothe slot 27 of the first unit, the coupling piece 41 will move throughchannel 35 in the projection 33, to engage the connector block 39,provided of course that the associated cams have properly been turned toan initial set-up position. Once fully interengaged, the two runner barsare interlinked so that they may slide simultaneously, in unison.

[0037] Referring now to FIGS. 6 and 7, there are shown two interlockunits 10 and 11 joined together, with their respective runner bars 17interlinked by coupling piece 41. The runner bars 17,18 are all in theirinitial setting, ready for the connection thereto of further interlockunits, should that be required. Such further interlock units may extendthe linear array shown in FIGS. 6 and 7, or may be added to the otherside walls of the units, so as to make up a complex two-dimensionalarray.

[0038] As shown in FIG. 7, if the right hand runner bar 17 is moved tothe right in the direction of arrow A by cam 22 (not shown in FIGS. 6and 7) upon rotation of the key receptor by an inserted key, that motionof the runner bar 17 will pull with it the corresponding runner bar 17of the left hand unit. Conversely, rotation of the key receptor of theleft hand unit, by an inserted key, so as to move the runner bar 17 ofthe left hand unit to the left, in the direction of arrow B, will pullwith it the right hand runner bar 17. Similar actions will be performedby the other interlinked runner bars of further added units, to theassembly.

[0039] For some applications, it may be desirable to cause the tworunner bars to move in unison when one bar is moved in one direction,but for that one bar to be independently moveable in the otherdirection. For this purpose, the groove 43 in coupling piece 41 may begiven a simple rectangular cross-sectional shape, rather than thedove-tail shape shown in FIGS. 5A and 5B. Then, on joining together thetwo interlock units, the connector block 39 will simply locate in thatgroove 43 but may move axially out of that groove, in use. Such acoupling piece is shown in FIG. 8; the right hand runner bar 46 may moveto the right without pulling the left hand runner bar 47. Moreover,runner bar 47 may move to the left without pulling runner bar 46.However, movement of either bar in the opposite sense will push theother runner bar in the same sense.

[0040] Another alternative would be wholly to omit the coupling piece41. In this case, either runner bar may push the other runner bar butthere is no other interconnection.

[0041]FIG. 9 shows an alternative actuator arrangement for a unit, toreplace the key-operated actuator shown in the previous Figures. Thebase part of the unit is the same as that described above, but the unithas a different cover plate 50 carrying a solenoid 51, having anarmature 52. The lower end of the armature is connected to a blockingplate 53 arranged above the runner bar 17 extending across the unit. Aspring (not shown) biases the blocking plate downwardly but onenergisation of the solenoid, the plate is lifted clear of the runnerbar. Below the runner bar, a switch 54 is mounted on the bottom plane 29of the unit 11, the switch picking-up in suitable holes 55 formedthrough the bottom plane, the switch sensing the position of the runnerbar 17.

[0042] In this arrangement, the blocking plate 53 serves to controlmovement of the runner bar either by blocking its movement, orpermitting its movement. In turn, this prevents or permits the movementof a runner bar in an adjacent unit of the interlock mechanism, underthe action of an actuator (such as a key-operated actuator) of thatadjacent unit. In an alternative arrangement, the blocking plate 50 mayinclude camming surfaces which serve to effect movement of the runnerbar of that unit. The supply of electrical power to the solenoid may beunder the control of a remote switch operated by some other component,such as a moveable machine guard.

[0043] Further units (not shown) may be employed in an interlockmechanism and having cover plates differently configured, for otheractuators such as a motor driven actuator to operate the runner bar ofthe unit, or to support a switch sensing the position of the runner bar.

[0044] It will be appreciated that though, in the drawings, only twointerlock units are shown, in a practical installation many suchinterlock units may be joined together. More complex interlockingarrangements may be provided by having the interlock units joined in agrid array, apart from a simple linear array as shown.

[0045]FIG. 10 illustrates a latch bolt mechanism for use with theinterlock assembly described above, for example to control the openingof a machine guard. A housing 57 is provided with a slot 58 of a similarform to the slot 27 of an interlock unit 10, so as to permitinterengagement with a projection 33 of such a unit. A bolt 59, directlyconnected for example to the machine guard to be protected, enters thehousing 57 through an opening 60 and has a conical head 61 formed at itsend, with an abutment face behind the head 61. A pair of gates 62 arepivotally mounted within the housing which gates are driven by the head61 on moving deeper into the housing, to the position shown. A bar 63 ismounted for sliding movement at right angles to the axis of the bolt 59and is spring-loaded to a position where the gates 62 may open to permitinsertion of the bolt 59. The end of the bar 63 engages the end of arunner bar of the interlock unit to which the housing 57 is joined, sothat until the appropriate keys have been inserted into their receptorsand suitably turned, the bar 63 cannot move to free the gates and sopermit the movement of the bolt 59 into the housing 57. In turn, thisprevents the machine guard being opened until the required safetyprocedures have been followed, in shutting down the machine andinhibiting its operation by removal of its keys and trapping the keys inthe interlock mechanism.

[0046] It will be appreciated that the interlock assembly may be used inmany other circumstances besides that described above, for a machineguard. For instance, electrical switches or other mechanical devices maybe controlled by the interlock mechanism, as is well known with existinginterlock mechanisms.

1. An interlock unit for use with at least one other like interlock unitto form an interlock mechanism, which interlock unit has a top face andopposed pairs of side walls, at least one runner bar mounted in the unitfor lateral sliding movement, an actuator for effecting lateral slidingmovement of the runner bar which actuator is supported on the top faceof the unit, one wall of an opposed pair thereof being provided with onepart of a two-part unit connector and the opposed wall with the otherpart of the connector, which connector is arranged to permit two similarunits to be joined together by relative sliding movement of the twounits in the plane of the side walls to inter-engage the respectiveconnector parts, the runner bar of one unit being engageable with therunner bar of a connected unit to transfer sliding motion thereto forsliding movement of the runner bar of said one unit in at least onedirection.
 2. An interlock unit as claimed in claim 1, wherein theactuator includes a receptor for a removable key, whereby insertion of asuitable key and turning the receptor operates the actuator.
 3. Aninterlock unit as claimed in claim 1, wherein the actuator includes asolenoid, whereby the supply of electrical power to the solenoidoperates the actuator.
 4. An interlock unit as claimed in any of thepreceding claims, wherein the unit connector allows the joining togetherof two units by relative sliding movement in a direction normal to thetop surfaces of the two units.
 5. An interlock unit as claimed in any ofthe preceding claims, wherein the one part of the unit connector definesa re-entrant slot on the one face of the unit and the other part definesa projection of a complementary form to the re-entrant slot whereby theslot of one unit and the projection of a second unit areinter-engageable by relative sliding movement of the units, along thelength of the slot.
 6. An interlock unit as claimed in any of thepreceding claims, wherein the runner bar is arranged for slidingmovement in a direction normal to the opposed pair of side wallscarrying the connector parts.
 7. An interlock unit as claimed in claim6, wherein a respective aperture is formed through each of the twoconnector parts in the opposed side walls and the runner bar is arrangedfor sliding movement in the apertures.
 8. An interlock unit as claimedin any of the preceding claims, wherein motion is transferred from onerunner bar of one unit to the runner bar of a connected unit by the endsof the respective runner bars abutting one another.
 9. An interlock unitas claimed in any of claims 1 to 7, wherein a coupling piece is providedon one end of the runner bar of one unit and is engageable with theopposed end of the runner bar of a connected unit.
 10. An interlock unitas claimed in claim 9, wherein the coupling piece permits either runnerbar of two connected units to move away from the runner bar of the otherunit but transfers the motion of one runner bar to the runner bar of aconnected unit for motion towards the other unit.
 11. An interlock unitas claimed in claim 9, wherein the coupling piece interconnects the tworunner bars of connected units, for transferring the motion of onerunner bar in either direction to the runner bar of a connected unit.12. An interlock unit as claimed in any of claims 9 to 11, wherein thecoupling piece is engageable in a radial direction with the end portionof a runner bar by transverse sliding movement with respect to the bar.13. An interlock unit as claimed in claim 12, wherein the coupling piecewhen mounted on the runner bar of one unit is arranged to inter-connectwith the runner bar of a second unit as the second unit is joined to theone unit by interengagement of the respective connector parts.
 14. Aninterlock unit as claimed in any of the preceding claims, wherein theunit is generally of rectangular shape having two pairs of opposed sidewalls, each pair of side walls having the two parts of a unit connectorwhereby a similar unit may be joined to any one of the side walls of theunit.
 15. An interlock unit as claimed in claim 14, wherein the unit hasa pair of runner bars arranged with their axes mutually at right anglesand each arranged to slide normally with respect to the two pairs ofside walls.
 16. An interlock unit as claimed in any of the precedingclaims, wherein a cam is rotatably mounted within the unit to effectsliding movement of the or each runner bar of the unit, which cam isrotatably coupled to the key receptor.
 17. An interlock mechanismwhenever assembled from two or more interlock units as claimed in any ofclaims 1 to 16.